blackheart malleable cast iron, the microstructure of which has a matrix, according to the grade specified, of various types of pearlite or other transformation products of austenite (see: blackheart malleable cast iron; compare: blackheart ferritic malleable cast iron), must tempermalm (tumeda murdega tempermalm), mille metallmaatriksi mikrostruktuurist moodustab valdava osa perliit või teised austeniidi laguproduktid (vt must tempermalm; vrd ferriitne must tempermalm)